[Criterion for determining the ionic specificity orders of membranes of biological and non-biological origin for univalent ions]

A formal criterion of membrane specificity for univalent ions is proposed: (see text), where Eg, El, and r stand for the energy of ion hydration, energy of ion interaction with the charged group (ligand) for the membrane, and ion crystalline radius respectively. Taking 5 cations: Li+, Na+, K+, Rb+, Cs+ as a model the existence of 16 lines of membrane ionic specificity out of 120 possible is predicted. On the basis of 4 anions: F--,Cl--,Br--,I--the existence of 8 lines out of 24 possible is predicted. 11 lines out of predicted cation lines and 7 out of anion lines were obtained by Eisenman.